Porsche PDK Coasting Feature Saving Fuel

[Carcharodon]

Whilst reading the Porsche website on the Cayman, I noticed that the PDK models disengage the engine whilst coasting. I thought coasting with engine disengaged used more fuel as the engine has to idle, whereas on the overrun it uses no fuel.

I can't get my head around this and I have searched the internet to no avail. Can anyone clear this up for me?

Thanks

[mollytherocker]

I thought this too but nope, overall coasting is better.

Its because there is no engine braking. So whilst you are using a little fuel at idle, the car rolls further.

I tried it for a week in my Insignia and improved my mpg by nearly 10%. But, you have to do it all of the time, ie, take it out of gear, every time you come off the throttle.

[truck71]

It's combined with the stop start feature and is utterly infuriating. Disengage button is the first I press when I get in the car; still returns mid to high 30's mpg commuting/ business mileage (Cayman 2.7).

[991fan]

My 991 even shuts the engine off before it stops! Engage sport button is the answer!

[av185]

Personally I like this feature....recently.had a new Cayman S PDK for a week and coasting is far easier by pulling both paddles simultaneously (like on the 458) rather than having to select neutral with the gearstick which somehow feels unnatural when coasting......

[thegoose]

I'd imagine that letting the gearbox self-coast is a lot safer than deliberately putting the car in neutral, because if you need to hit the gas in an emergency drive will be there, not so if in neutral.

[Little Lofty]

I barely notice it on mine, although that's maybe because I usually have the sport button pressed.It doesn't bother me when it's doing its thing and helps me get nearly 40 mpg on a run, I guess if it didn't save fuel Porsche wouldn't have introduced it.

[ORD]

I do this myself if going slowly down a hill - you can really feel the engine braking in 1st and 2nd so I expect it saves a fair bit of fuel in traffic. I imagine it would annoy me,e on the motorway .

[Radish]

I'm with truck71, metaphorically speaking of course.

Edited by Radish on Saturday 22 February 16:38

[cvega]

https://www.youtube.com/watch?v=juDfN1pA1ZY

[stevod]

thegoose said:

I'd imagine that letting the gearbox self-coast is a lot safer than deliberately putting the car in neutral, because if you need to hit the gas in an emergency drive will be there, not so if in neutral.

Indeed. And you can also force in-gear coasting with an up-shift from 7th.